The patent literature 1 discloses an electromagnetic clutch that has a thermal fuse. When a compressor is locked, the thermal fuse is melted and is open-circuited by frictional heat, which is generated between a friction surface of an armature and a friction surface of a rotor. Thus, supply of an electric current to an electromagnetic coil is blocked, and thereby the electromagnetic clutch is placed into a drive-force-blocking state.
In the electromagnetic clutch recited in the patent literature 1, a portion of the thermal fuse is exposed from a resin member, which holds the thermal fuse, so that radiant heat, which is generated at the friction surface of the rotor, can reach the thermal fuse.
However, even when the radiant heat reaches the thermal fuse, a portion of the radiant heat, which has reached the thermal fuse, is reflected by and is escaped from the thermal fuse without being absorbed by the thermal fuse. Thus, in order to improve the responsiveness of the thermal fuse, it is desirable that the radiant heat, which is reflected by the thermal fuse, is absorbed by the thermal fuse.